A Thai court began handing down guilty verdicts Wednesday at the culmination of the country’s largest ever human trafficking trial, Reuters reports.

Bangkok’s Criminal Court Division for Human Trafficking had been trying 103 suspects — including 20 government officials and a Thai army general — accused of trafficking stateless Rohingya Muslims from Myanmar and Bangladeshi nationals across the Thai-Malaysia border.

Thai authorities began making arrests in 2015 after dozens of trafficking victims were found buried in a mass grave in a jungle in the country’s south. Some of the suspects in the case face life imprisonment for human trafficking, holding people for ransom, murder, and other crimes.

Only one of 22 defendants whose cases concluded in a morning session was found not guilty, according to Reuters. More guilty verdicts are expected to follow.

Southeast Asia-based non-profit Fortify Rights called the trial an “unprecedented effort by Thai authorities to hold perpetrators of human trafficking accountable” in a press release Tuesday, but noted that the proceedings were beset by threats against witnesses, interpreters and police investigators.

“It’s been a rocky road, and it’s not ‘case-closed’ for survivors of human trafficking here,” Amy Smith, an executive director at the non-profit, said in the release. “Thailand has a long way to go to ensure justice for thousands who were exploited, tortured, and killed by human traffickers during the last several years.”

Fortify Rights also noted that authorities had arrested only 103 suspects out of 153 who were named on official arrest warrants issued in connection with the investigation. In a separate interview with Reuters, Smith said that while the crackdown had disrupted human trafficking in Thailand, the illicit network remains “well in place.”

Thailand has long been a source, transit route and destination for human trafficking from poorer neighboring countries such as Myanmar, Cambodia and Laos. Just last month, the U.S. State Department kept Thailand on the Tier 2 Watchlist in its annual Trafficking in Persons (TIP) Report — the second lowest ranking — for what were deemed insufficient efforts to combat human smuggling and trafficking.

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